Test xgcm generate_grid_ds on cubed-sphere grid (2D curvilinear)

autogenerate_cubedsphere.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```\n",
    "pip install git+https://github.com/JiaweiZhuang/cubedsphere.git\n",
    "```"
   ]
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   "cell_type": "code",
   "execution_count": 1,
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   "source": [
    "import numpy as np\n",
    "import cubedsphere as cs"
   ]
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   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "dict_keys(['lon', 'lat', 'lon_b', 'lat_b'])"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "csgrid = cs.csgrid_GMAO(12)\n",
    "csgrid.keys()"
   ]
  },
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   "cell_type": "code",
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     "name": "stdout",
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     "text": [
      "lon (6, 12, 12)\n",
      "lat (6, 12, 12)\n",
      "lon_b (6, 13, 13)\n",
      "lat_b (6, 13, 13)\n"
     ]
    }
   ],
   "source": [
    "for k in csgrid:\n",
    "    print(k, csgrid[k].shape) # 6 is the number of cubed-sphere faces"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "def test_bound_2d(center, bnd, decimal=1):\n",
    "    center_inferred = 0.25*(bnd[1:,1:] + bnd[1:,:-1]+bnd[:-1,1:] + bnd[:-1,:-1])\n",
    "    \n",
    "    # don't be too strict. The center of a cuvilinear cell is not strictly equal to the average of the 4 corners\n",
    "    # just use a low-precision checking here\n",
    "    np.testing.assert_almost_equal(center, center_inferred, decimal=decimal)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "# test a single panel\n",
    "test_bound_2d(csgrid['lat'][0], csgrid['lat_b'][0])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [],
   "source": [
    "# test all panels\n",
    "for i in range(6):\n",
    "    # decimal=1 will fail at a few cells\n",
    "    test_bound_2d(csgrid['lat'][i], csgrid['lat_b'][i], decimal=0)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "TODO: replace `csgrid['lat_b']` by auto-generated boundaries generated by xgcm.\n",
    "\n",
    "NOTE: `lon` is tricker to check because any `lon+360*n` should be considered as equal to `lon`. A more robust comparison should be done in cartesian `(x, y, z)` space."
   ]
  }
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